1. Technical Field
The present disclosure relates to a display device and, more particularly, to a display device that generates sound by vibrating a display panel.
2. Discussion of the Related Art
With the development of various portable electronic devices, such as a mobile communication terminal and a notebook computer, a desire for a flat panel display device applicable thereto is increasing. The flat panel display devices include a liquid crystal display (LCD) device, an electroluminescence display device, a light-emitting diode (LED) display device, and an organic light-emitting diode (OLED) display device.
Among these display devices, the liquid crystal display (LCD) device includes an array substrate including an array of thin film transistors, an upper substrate including a color filter and/or a black matrix, etc., and a liquid crystal material layer formed therebetween. An alignment state of the liquid crystal is controlled according to an electric field applied between two electrodes of a pixel area, and thereby, the transmittance of light is adjusted to display images.
In a display panel of such a liquid crystal display device, an active area (AA) configured to provide an image to a user and a non-active area (NA), which is a peripheral area of the active area, are defined. The display panel is usually manufactured by attaching a first substrate, which is an array substrate having a thin film transistor formed therein to define a pixel area, and a second substrate, which is an upper substrate having a black matrix and/or color filter layer formed thereon, to each other. The array substrate or first substrate, on which a thin film transistor is formed, includes a plurality of gate lines extending in a first direction and a plurality of data lines extending in a second direction perpendicular to the first direction. One pixel area is defined by each gate line and each data line. One or more thin film transistors are formed in one pixel area, and gate and source electrodes of each thin film transistor may be respectively connected to a gate line and a data line.
Among these display devices, the liquid crystal display device does not have its own light-emitting element, and thus needs a separate light source. Therefore, the liquid crystal display device has a back-light unit having a light source, such as an LED, which is arranged at the rear surface thereof and irradiates a light toward a front surface of the liquid crystal panel thereof, thereby implementing a recognizable image.
Recently, an organic light-emitting diode (OLED) display device coming into the spotlight as a display device has advantages of a fast response time, high light-emitting efficiency, high luminance, and a wide viewing angle by using an OLED that emits light by itself, i.e., is “self-emitting.” In the OLED display device, sub-pixels including organic light-emitting diodes are arranged in a matrix form, and the brightness of sub-pixels selected by a scan signal is controlled according to a grayscale of data. Further, the OLED display device, which is an emissive element, consumes a small amount of power and has a high response speed, a high light-emitting efficiency, a high luminance, and a wide viewing angle.
Meanwhile, a set device or a finished product including such a display device as described above may include, for example, a television (TV), a computer monitor, or an advertising panel. Such a display device or set device may include a sound output device, such as a speaker, for generating and outputting sound relating to a displayed image.
Typically, a company that manufactures a display portion of a device, such as a liquid crystal display device or an organic light-emitting diode display device, manufactures only a display panel or a display device, while another company that manufactures a speaker assembles the speaker with the manufactured display portion, to complete a set device capable of outputting images and sound. The reverse assembly may also be done, but still in two parts and often in different manufacturing facilities.
FIG. 1 is a plan view of a speaker included in a related art display device.
As shown in FIG. 1, the related art display device 1 or a set device includes a speaker 2 disposed on a rear part or a lower part of a display panel thereof. In this structure, the sound generated by the speaker 2 does not progress directly toward a viewer, who is viewing an image from the front side of the display device 1, but progresses toward the rear part, the lower part, or the edge of the display panel, rather than the front part of the display panel on which the image is being displayed. Therefore, the sound's mismatched directionality may disturb the viewer's immersion experience. In addition, when the sound generated from the speaker 2 progresses toward the rear part, the lower part, or the edge of the display panel of the display panel, the sound quality may be degraded due to an interference with sound reflected by walls, floors, or other surfaces at the rear of or below the display panel.
In addition, the sound generated by a speaker included in the related art display device is not oriented toward a viewer of the display device, and may thus undergo diffraction, which further degrades the sound localization. Moreover, in configuring a set device, such as a TV, a speaker may occupy an undesirably large amount of space, which imposes a restriction on the design and spatial disposition of the set device. In mobile devices, for example, the speaker takes up space that forces a larger size in thickness and/or bezel area.
Therefore, there has been an increasing desire for a technology which can improve the quality of sound output from a display device and reduce the viewer's immersion experience from being disturbed. According to such a need, a technique for generating sound by directly vibrating a display panel of a display device has recently been developed.
Such a panel vibration type sound-generating device may have a configuration in which a sound-generating actuator is fixedly inserted into a support hole formed in a cover bottom or the like, which is a rear support structure of a display device. In this case, generated sound leaks out through the support hole formed in the cover bottom, which may degrade a sound-generating characteristic, and the leaked sound may be reflected from a rear wall so that the reflected sound is output to the front side where a viewer is positioned, which may cause the sound quality to be deteriorated due to sound interference.